What a difference a few days can make. Until Friday morning, Discovery Channel's "American Guns" was generally regarded as a popular, not especially complicated show about the travails of a family of gun sellers. In the aftermath of the devastating murders at Sandy Hook Elementary School, the show's become a symbol of our culture's fraught but durable love affair with guns. After hundreds of Facebook users besieged the show's page, calling for its end, they got their wish. The network has cancelled the show.